kasetsart journal natural science

84
initials at the time of pinning are recorded in the
wound tissue (Nobuchi et al., 1995). This method
mostly has been applied to the study of temperate
zone trees (Shimaji and Nagatsuka, 1971; Kuroda
and Shimaji, 1983, 1984) and rarely applied to
tropical trees.
For the pinning method to tropical trees,
Shiokura (1989) and Nobuchi et al. (1995, 1996)
used a nail instead of a pin because tropical trees
have generally thick and hard bark. The wound
tissues induced by either a pin or a nail insertion
were short in longitudinal direction, therefore, it
was difficult to obtain appropriate sections from
the center of tiny wound tissues. To make this
method easier “knife-cutting method” proposed by
Fujiwara (1992) was the alternative method to
improve the pinning method. Kuroda and Kiyono
(1997) investigated the seasonal rhythms of xylem
growth measured by knife-cutting method that
they called the wounding method.
The researches of the seasonal
characteristics of wood formation of genus
Eucalyptus are very much limited. Ogata et al.
(1996) analysed the seasonality of wood formation
in E. tereticornis and E. saligna by knife-cutting
method and Kondo et al. (1996) analysed the radial
growth in E. dalrympleana by knife-cutting
method. Particularly, the radial growth compared
among clones of E. camaldulensis are not reported.
In this report, the knife-cutting method
was applied to compare the radial growth among
Kasetsart J. (Nat. Sci.) 40(1)
5 superior clones of E. camaldulensis and the data
were discussed in correlation with the climatic data
near the plantation site. The objective of this study
aims to screen for the eucalyptus clone which is
fast growing even in dry condition.
MATERIALS AND METHODS
Five superior clones of six-year-old E.
camaldulensis in the plantation site at Sakaew
province in eastern part of Thailand were selected
as sample trees. The name of clones were T5, Kitti,
S9, Y2 and K2, which were coded in this report as
clone 1, 2, 3, 4 and 5, respectively. Diameter at
breast height ranged from 18.5 to 24.1 cm.
Knife-cutting method
Knives of 0.5 mm in thickness and 10
mm in width were used for marking. To investigate
radial growth around the trunk, marking positions
were done at four sides of trunk (southwest side
and opposite, southeast side and opposite). The
knife was inserted deep enough to reach the border
of cambium and xylem and removed immediately.
As shown in Figure 1, the distance between two
points was about 4 cm in tangential direction and
about 10 cm in longitudinal direction. The
marking was done every month from August 1998
to July 1999. Table 1 indicates the dates of
marking.
Blocks of 3 cm in radial depth containing
� � � � � �
Aug. 98 Oct. 98 Dec. 98 Sep. 98 Nov. 98 Jan. 99
� � � � � �
Feb. 99 Apr. 99 Jun. 99 Mar. 99 May. 99 Jul. 99
Southwest side Southeast side
Figure 1 Schematic illustration of the marking point on a trunk.